Nickel 1-m Telescope Manual: Observing Hints

Observing Hints

Listed here are some basic procedures often performed when using the Nickel Telescope.

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Homing the Telescope | Pointing Check and Setting Guider Fiducial | Dome Flats | Telescope Focus | Guider Focus

Homing the Telescope

On the afternoon of the first night of an observing run, it is advisable to home the telescope before opening the dome for the night. On rare occasions, it may be necessary to home the telescope during the night (e.g. when you can't find a star or there is a mechanical problem).

Homing the telescope is best done with the dome closed (always close the mirror cover before opening or closing the dome), so that wind buffetting doesn't affect the telescope as it finds its fiducials.

The homing GUI can be brought up from the POCO software by clicking on Functions - Home Telescope.... Once the Telescope Homing Control GUI is up, click on Slew Home for both the HA and Dec axes (both axes can be homed at the same time). The state will count down from "10 - Slew Home" to "1 - Axis is Homed". Normally homing takes less than 10 minutes. If for some reason homing fails, contact a support astronomer or telescope technician for assistance.

Pointing Check and Setting Guider Fiducial

Finding the first star of the night and fine tuning the pointing of the telescope is usually done during twilight (usually after twilight flats are completed). To check pointing do the following:

Enter coordinates and epoch of a bright star near zenith into the POCO GUI. A good source for finding stars is the Astronomical Almanac - the current edition is available in the Nickel ROR. An on-line resource for bright stars is KPNO's edited list of Almanac Bright Stars.
Click Move to Target in the POCO GUI (make sure that telescope motion is enabled, tracking and autodome are on).
Once telescope is "On Target":
- Direct Imaging:
  1. With "CCD is On Axis", take a short exposure (e.g. 1 second) with the science camera. If star is not centered, move the telescope (using the "Offset Telescope" function in POCO) to center the star and take another exposure. Repeat until object is centered on the detector.
  2. Click Mark Centered in POCO GUI.
  3. Change to "Guider is On Axis" with POCO GUI.
  4. Choose a numbered marker in the Guider image display and position it at the position of the bright star. This position will correspond to the center of the science CCD.
- Spectrograph:
  1. With "Diagonal Out", place the guide reticle at the desired position on the slit (usually the center)
  2. Place the bright star at guide reticle position on the slit. If you can't find the bright star, put the "Diagonal In" to get a wider field of view for acquiring the star. Position the star in the center of the upper half of the guider field of view and take the "Diagonal Out". Star should now be visible in the narrower field of view of the slit viewing camera.
  3. Click Mark Centered in POCO GUI.
  4. Put the "Diagonal In" via the POCO GUI.
  5. Choose a numbered marker in the Guider image display and position it at the position of the bright star. This marks the desired slit position on the wider field view for field acquisition.
If you can't find the bright star, click on Object Not Found... in the POCO GUI. This will lead you through some basic steps and things to check to help you find a star. If all else fails, contact a support astronomer for assistance.

Dome Flats

Procedures for doing dome flats depends on the instrument. Refer to the following for details:

Telescope Focus

Focusing the telescope involves moving the secondary mirror up or down via the POCO Focus Telescope GUI.

Focus procedures are instrument specific. Please refer to the following for details:

Direct Imaging Focus Procedure
Spectrograph -
1. Make sure guider is properly focused on the slit (see Guider Focus below)
2. Position a star near the slit (but not on it). Make sure star is not saturating the guide camera.
3. Move the secondary mirror (steps of 3 or 5 counts are typical moves for coarse focusing) while watching the star on the guider. Continue changing the focus until you have the roundest, most compact stellar image possible.

Guider Focus

Procedure depends on the instrument:

Direct Imaging Camera:
1. Make sure telescope is focused on the CCD camera (see Telescope Focus above).
2. Make sure a bright, but unsaturated star is visible in the guider field of view.
3. Move the "trombone" mirrors for the guider via the Naux_fe GUI in or out until you find the best focus.
Spectrograph: Refer to Focusing the Guider on Slit.

Last modified: Thu Mar 30 10:01:01 PDT 2017

User's Guide to the Nickel 1-m Telescope

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